This project will investigate how Drosophila controls the expression of its Alpha-tubulin genes. The four genes of this small multigene family offer a good opportunity to investigate the control of tissue- and time-specific transcription and to investigate mRNA characteristics that determine mRNA stability and location. The issues to be dealt with in this investigation are: 1) the location and complexity of DNA sequences that cause one family member's transcription pattern to deiifer from that of another member; and 2) whether or not there are sequences in the mRNAs from different family members that cause them to differ in fate, that is to differ in intercellular transport, in cellular location and in stability. In pursing the first issue, regions and sub-regions will be exchanged between the Alpha-tubulin genes and the resulting genes used to transform Drosophila. The pattern of expression of these altered genes will indicate which sequences are necesssary for a particular tissue- or time- specific pattern of transcription. In pursuing the second issue, portions of the mRNA encoding regions of Alpha-tubulin genes will be excahanged with portions of other genes and then a transformation assay will be used to test the effect of 3 prime and 5 prime untranslated regions, introns and translated regions on the intercellular transport, the location and the stability of Alpha-tubulin mRNAs. The initial subjects for these exchanges will be an Alpha-tubulin gene which codes for a maternal mRNA, one which codes for an mRNA that first appears between egg laying and cellular blastoderm formation and one which appears to be transcribed at all times in all tissues.